The halo model [1]}, [2]}, [3]}, [4]} makes the assumption that all matter resides in virialized halos of mass \(M_{\rm {vir}} = \frac{4}{3} \pi R_{\rm {vir}}^{3} \Delta _{\rm {vir}} \bar{\rho }_{m}\) , and splits the two-point statistics of the matter field into correlations between halos (two-halo term) and correlations within a single halo (one-halo term):
\(P_{mm}(k) = P_{1h}(k) + P_{2h}(k),\ \xi _{mm}(r) = \xi _{1h}(r) + \xi _{2h}(r).\) 
